Effect of contemporary infestation by the spruce aphid (Elatobium abietinum) on root growth in Sitka spruce transplants

The short-term relative effects on root growth of aphids living on the needle leaves of spruce transplants were examined experimentally. Ultimately, aphids cause the loss of foliage and so defoliation was simulated in two of the treatments. Aphid populations at a density frequently reached in forest conditions, caused no relative inhibition in root growth over a 62-day period. Aphids were expected to have a longer term impact, however, since artificial defoliation had significant effects on root development.